Newbie as well, but so far what I figured out:
* Yesterday I figured out that you can use Highlighter to upload or link videos.
* To show the video in my Primal / Amethyst, I right click on the video and copy video address which I then post in my prefered client.
* I have a Npub.pro website and to have my articles show there, I write them in Highlighter long form and add a tag that is also in my Npub.pro site and it then shows up there.
* Don't know much about Fountain but great for loading podcasts.

Hope this helps somewhat.